URL reformatting issue with Requests_IRI

When requesting an URL with a fragment, the reformatted URL can be different from the original one. The following example rewrites https://example.com/#foobar to https://example.com#foobar instead of returning the same URL.
As a consequence, curl fails to load the URL.

``` php
$url = "https://example.com/#foobar";
$iri = new Requests_IRI($url);
$url = $iri->uri;
var_dump($url);
```
